Biodiversity: India & World| Extinction & Endangered Species

Biodiversity: India & World| Extinction & Endangered Species

What is Biodiversity?

• Biodiversity is a combination of Greek word Bios (=life) and Latinword Diversitas (= variety).Biodiversity literally means Variety of life in ecology, biodiversity refers to the diversities (number & variety of species) of plant and animal life within a region. In this way we can say, as far as the extent of biosphere, there is biodiversity i.e. variety of life. Inversely, as far as variety of life possible, up to that extent there be biosphere.

• In our biosphere immense diversity exists. The known and described number of species of all organism on the earth is approx. 1.7-1.8 million, which is fewer than 15% of the actual number.

Level of Biodiversity

• The term Biodiversity was first coined by Waller G. Rosen (b.1929) in 1985, but this term is populated by the American sociobiologist Edward Osborne (E.O)Wilson (1929-2021), to describe the combined diversity at all hierarchical levels of biological organisation. E.O. Wilson is revered as the Father of Biodiversity'.
• Biological diversity includes three important hierarchical levels-Genetic, Species and Community & Ecosystem diversity. These levels of biodiversity are interrelated, yet district enough to studied separately.

1. Genetic Diversity

Genetic diversity refers to the variation of genes within species. Each species stores an immense amount of genetic information. For example, the numbers of genes is about 35,000 to 45,000  in Homo Sapiens. India has more than 50,000 genetically different strains of rice and 1,000 varieties of mango. The amount of genetic variation in the basis of speciation (evolution of new species). It has a key role in the maintenance of diversity at species and community levels. Genetic diversity within a species often increases with environmental variability.

2. Species Diversity:

Species diversity refers to the variety of species within a region. For example, Western Ghats have a greater amphibion species diversity than the Eastern Ghats. Species are distinct unit of diversity e.ach playing a specific role in an ecosystem. Therefore, loss of species has consequences for the ecosystem as a whole.

3. Community and Ecosystem Diversity:

According to Whittaker (1972), diversity at the level of Community and Ecosystem has three perspectives—Alpha, Beta & Gamma diversity.

Alpha Diversit:

Diversity of organism within-community diversity is called Alpha diversity. Alpha diversity refers to the diversity of organism sharing the same community/habitat.

Beta Diversity:

Diversity of organism between communities (i.e. in ecosystem) diversity is called Beta diversity.

Gamma Diversity:

Diversity of habitat over the total landscape or biome is called Gamma diversity.

Biodiversity in World

• The World Conservation Union—WCN (formerly known as International Union for the Conservation of Nature and Natural Resources—IUCN) issues biodiversity-related reports from time to time. But we have no clear idea of how many species are yet to be discovered and described. Estimates vary widely and many of them are only educated guesses.
• Some extreme estimates range from 20 to 50 million, but a more conservative and scientifically sound estimate made by Australian ecologist Rokeri May (1936-2020) places the global species diversity at about 7 million. More than 70% of all the species recorded are animals, while plants (including algae, fungi, angiosperm etc.) comprise no more than 22% of the total. Among animals, insects are the most species-rich taxonomic group making up more than 70% of the total. Among plants, fungi and angiosperms are the most species-rich taxonomic group, making up about 14% and 14% separately of the total.
• Biodiversity varies with changes in latitude and altitude. In general, species diversity increase as we move away from the poles towards the equator. Similarly, we generally notice a decrease in species diversity from lower to higher altitude on a mountain.
• It is notable that more complex and heterogenous the physical environment, more complex and diverse will be the flora and fauna.

Biodiversity in India

• Although India has only 2.4 % of the world's land area, its share of the global species diversity is an impressive 8.1%. That is what makes our country one of the 12 mega diversity countries of the world. The largely, tropically Amazonian rainforest in South America has the greatest biodiversity on earth.
• If we accept May's global estimates, only 22% of the total species have been recorded so far. Applying this proportion to India's diversity figures we estimate that there are probably more than 1 lac plant species and 3 lacs animal species yet to be discovered and described. Nature's biological library is burning even before we catalogues the titles of all the books stocked there.
• In India, we are endowed with a rich diversity of the biogeographically distinct regions due to varying physical conditions and species groupings. Among the biogeographical regions, Deccan peninshula has the most extensive coverage of Indian landmass (42%). The most biodiversity rich zones, North-East account for 5.2% and Western Ghats account for 4% of the geographical area.
• A large number of species found in these zones are endemic or exclusive to India. About 33% of flowering plants, 53% of freshwater fish, 60% of amphibian, 36% of reptile and 10% of mammals are endemic to our country. The endemics are concentrated mainly in North-East, Western Ghats, North-West Himalaya and Andman& Nicobar Iselands.

Uses of Biodiversity

Humans derive many direct and indirect benefits from the living world. The uses of biodiversity are briefly described below—

1. Source of Food and Improved Varieties:

Biodiversity is of use to modem agriculture in three ways—

(a) as a source of new crop,

(b) as a source material for breeding improved varieties, and

(c) as a source of new biodegradable pesticides. Of the several thousand of edible plants, less than 20 plant species are cultivated to produce about 85% of the world's food; in which 3 plant species of wheat, corn and rice (three major carbohydrate crops) yield nearly 2/3 (66.66%) of food sustaining the human population. Fats, oils, fibres, etc. are other uses for which more and more new species need to be investigated.

The domesticated species are crossbred with their wild relatives to improve their traits. Genes of wild species are used to confer new properties, such as disease resistance or improved yield in domesticated species. For example, rice grown in Asia is protected from the four main diseases by genes received from a single wild rice species (OryzaNivara) from India.

2. Drugs and Medicine :

Biodiversity is a rich source of substance with therepeutic properties. For example/ Morphin (Papaver Somni (ems), used as an analgesic, Quinine (ChinchonaOfficinalis), used for the treatment of Malaria, and Taxol, an anticancer drug obtained from the bark of the yew tree (TaxusRevifolia, TaxusBaccata).

3. Aesthetic and Cultural Benefits:

Biodiversity has also great aesthetic value. Example of aesthetic aspects includes ecotourism, bird-watching, wildlife (jungle safari etc), pet keeping, gardening etc. In a majority of Indian villages and towns, plants like Tulsi (Ocimum Sanctum), Neem (AzadirachtaIndica), Pipal (Ficus Religiosa), and Khejri (Prosopis Cineraria) and various other trees are planted, which are considered sacred and worshipped by people. Several animals [like oxen (cow-bull), horse etc.), birds and even snake, have been considered sacred.Today, we continue to recognise plants and animals as symbols of national pride and cultural heritage. For example, National Flower—Lotus (NelumboNucifera), Nation tree— Indian Banyan (FicusBenghalensis), National Fruit—Mango (MangiferaIndica)-, National Bird—Indian Peacock (PavoCristatus), National Reptile—King Cobra (Ophiophagushannah), National Animal—Tiger (Pantheratigris), National Aquatic Animal—Ganges River Dolphin (PlatanistaGangetica), National Heritage Animal—Indian Elephant (Elephas Maximus Indicus)

4. Ecosystem Services:

Biodiversity is essential for the maintenance of ecosystem and their sustainable utilisation. These services include maintenance of gaseous composition of the atomsphere, climate control, by forests and oceanic systems, natural pest control pollination of plants by insects and birds, formation and purification of water and nutrient cycling etc.

Loss of Biodiversity

• The accelerated rates of species extinction that the world is facing now are largely due to human activities. There are four major causes ('The Evil quartet'is the sobriquet used to describe them) of biodiversity losses—habitat loss and fragmentation, introduction of exotic (alien, species, over-exploitation and co-extinctions. The other causes of biodiversity losses are environment pollution, encroachment of forestland, deforestation, etc.

1. Habitat Loss and Fragmentation:

The destruction of habitat is the most important cause for the losses of biodiversity. The most dramatic examples of habitat loss come from tropical rain forests. Once covering more than 14% of the earth's land surface, these rain forests now cover only 6%. The Amazon rain forest (it is so huge that it produces 20% of the total oxygen in the earth's atmosphere through photosynthesis. Thus, it is called the lungs of the planet) is being cut and cleared for cultivation of soya beans or for conversion to grasslands for raising beef cattle.

When people cut down trees, fill a wetland, plough a grassland or burn a forest, then large habitats break up into small fragments. A forest patch surrounded by couplands, orchards, plantation and an urban areas are examples of fragmented habitats. With the fragmentation of a large forest tract, species occupying deeper parts of forests are the first to disappear. When fragmentation is occured due to various human activities, mammals and birds requiring large territories and certain animals and birds with migratory habits are badly affected, leading to reduce size of its population to an exent that it becomes vulnerable to extinction.

2. Introduction of Exotic/Alien Species:

New species entering a geographical regions are called exotic or alien species. When exotic/alien species are introducd unintentionally or deliberately for whatever purpose, some of them turn invasive, and cause decline or extinction or disappearance of indigenous or native species. Invasive species are considered second only to habitat destruction as a major cause of extinction of species. Exotic/alien species are having large impact espeically in island ecosystem, which harbour much of the world's threatened biodiversity.

A few examples are—

1. Invasive weed species: Carrot grass (Parthenium), Lantana eamara, Water hyacinth (Eicchornia) etc. We are familiar with the environmental damage caused and threat posed to our native species by invasive weed species like Carrot grass, Lantana, Water hyacinth etc.
2. Predatory fisher: Nile perch, African catfish (ClariesGariepinus) etc. Nile perch, an exotic/alien fish introduced into Lake Victoria (South Africa) threatens the entire ecosystem of the lake by eliminating several native species of the small cichlid fish species that were endemic (unique) to this freshwater aquatic system. Similarly, the recent illegal introduction of the African catfish (ClariasGariepinus) for aquaculture purposes is posing a threat to the native catfishes of India.

3. Over-exploitation:

Humans have always depended on nature for their three basic needs—food, cloth and shelter (as symbolically said in Hindi Roti, Kapada & Makaan), but when 'need' turns to 'greed'. It leads to over-exploitation of natural resources. Many species extinction in the history (e.gsteller'ssea cow, passenger pigeon) were due to over-exploitation by humans. Presently many marine fish population around the world are over harvested, endangering the continued existance of some commercially important species.

4. Co-Extinctions:

When a species becomes extinct, the plant and animal species associated with it an obligatory way also become extinct. In the case of coevolved plant-pollinator mutalism, extinction of one invariably leads to the extinction of the other. When a host fish species becomes extinct, its unique assemblage of parasites also meets the same fate.

Extinction of Species

Extinction is a natural process. Species have disappeared and new ones have evolved to take their place over the long geological history of the earth.

There are two major ways of extinction process—

1. Natural/Background Extinction:

With the change in environmental conditions, some species diasppear and other, which are more adapted to changed conditions, take their place. This loss of species which occured in the geologist past, at a very slow rate, is called natural or background extinction.

2. Anthropogenic/Man-made Extinction:

An increasing number of species are disappearing from the face of the earth due to human activities. This man-made mass extinction represents a very severe depletion of biodiversity, particularly because it is occuringwithin a short period of time.

The world conservation monitoring centre has recorded that 384 plant species (mostly flowering plants) and 533 animal species (mostly vertebrates) have become extinct since the year 1600. The earth may lose up to 50% of the species by the end of the 21st century, if the current rate of loss continues.

Susceptibility to Extinction:

Susceptibility means the state of being susceptible (easily submittable). The characteristics of species particularly susceptible to extinction are large body size (Bengal tiger, lion and elephant); small population size and low productive rate (Blue whale and Giant panda). Feeding at high trophic levels in the food chain (Bengal tiger and Bald eagle), fixed migratory routes and habitat (Blue whale and Whooping crane)and localised and narrow range of distribution (Woodland caribou)-, many island species also make the species susceptible to extinction.

The WCN (Former IUCN) Red List/Red Data Book

• The WCN / IUCN Red list is a catalogue of taxa that are facing the risk of extinction. It is important to understand that the Red List aims to impart information about the urgency and scale of conservation problem to the public and policy makers.

The uses of the Red Lists:

The uses of Red list are—

1. Developing awareness about the importance of threatened biodiversity;

2. Identification and documentation of endangered species;

3. Providing a global index of the decline of biodiversity and

4. Defining conservation priorities at the local level and guiding conservation action.

• The WCN/IUCN has0 recognised five (during 1963-99), after that eight (in 2000) and at last nine Red List categories in (2012) of species.
• The nine Red List categories are defined in table below.

The WCN/IUCN Red List Categories

Endangered Species of India

Vulnerable Species:

Species whose population has still not reduced but face the threat of extinction as the casual factors like reduction in habitat can be easily observed.

Example: Black buck, Spotted deer, Golden langur, Asiatic wild ass etc.

Rare Species:

Species that at present neither vulnerable nor endangered but at risk are called rare. The species which have small populations in world and are confined to limited areas or thinly distributed over a more wide area.

Example:  Asiatic pheasants, Satyr tragopan, Temminicktragopan etc.

Threatened Species:

Species which are under the threat of extinction and whose survival is unlikely if the casual factors like habitation loss continue operating. Threatened species includes three categories. Critically Endangered, Endangered & Vulnerable.

Extinct:

Aparticular species is considered extinct when its last surviving member dies and has not been seen in wild for the last 50 years.

Example: Dodo, Passenger pigeon etc.

Critically Endangered:

Sumatran Rhinoceros (found in foothills of the Himalaya in N-E India & Bhutan), Himalayan Brown or Red Bear, Kondana Soft-furred Rat (found in Singhgarh plateau near Pune), Elvira Rat or Large Rock Rat (found in Kurumbapatti, Salem district, Tamil Nadu),

Namdapha Flying Squirrel (found in Namdapha National Park, Arunachal Pradesh), Malabar Large-spotted civer (found in Western Ghats),

Endangered Asiatic Wild Dog/Dhole or Indian Wild Dog (found in Western Ghats & Eastern Ghats, Centre’ Indian highlands, West Bengal, Assam and Arunachal Pradesh), Browantlered Deer/Eld's Deer &Thamin (found in KeibulLamjao National Park, Manipur), Golden Langur (found in moist evergreen & moist deciduous forests). Indian Hog deer (found in Northern & North-Eastern India), Lion tailed Macaque (found in Western Ghats), NilgiriTahr (found in western Ghats).

Vulnerable Species:

Greater onehom Rhino (foundin Northern India), Sloth Bear (found in Northern India), NilgiriLangur (found only in Western Ghats), Binturong (found in Sikkim, Capped Langur (found in A.P., N-E India), Cheetah (found in central India), Clouded Leopard (found in Himalayan foothill), Dugong / Sea cow (found in Laccadives, Andaman & Nicobar), four-horned Antelope (found in Himalayan foothill & peninsular India), India Gaur (found in mainland, Sambar (found in India).